I’d check the Watch app on your iPhone first. Go to My Watch > Apps > Available Apps and see if Waterspeed or what3words appears there.
You can also try installing either app directly from the App Store on your Apple Watch.
If the apps appear but won’t install, try restarting both your iPhone and Apple Watch.
Are the apps missing from the Available Apps list, or does tapping Install simply not do anything? That would help narrow down the issue.
A friendly note: This is the German-language Apple Support Community. Posting your question in German will make it easier for more members to understand it and offer assistance.